Six major and four minor users at the University of Minnesota are requesting instrumentation needed to study the structure and function of enzymes, muscle proteins, apolipoproteins, bacterial toxins, and metalloproteins. These instruments will be used to provide a vital linkage of thermodynamic and dynamic properties to ongoing structural analyses. The investigators are studying biological function through mutagenesis and protein design, using the shared facilities of a recently established Structural Biology Core Laboratory at the University of Minnesota. A dynamic light scattering instrument will be employed by all of the users to analyze the aggregation state of proteins that are being designed and produced. Understanding the oligomeric state of a protein or protein complex is essential to NMR studies, to the preparation of crystals for X-ray diffraction, and to a variety of spectroscopic analyses. A titration calorimeter will be used by three major and three minor users to determine the energetics of protein ligand binding, which is often required for the functional characterization of mutant or covalently modified proteins in structural studies. A multifrequency phase fluorometer will be used by three major and three minor users to analyze protein dynamics, structure, and protein-protein interactions. This particular emphasis will be placed on the use of mutagenesis to engineer labeling sites for fluorescent probes in proteins, providing site-specific structural and dynamic information to complement x-ray and NMR structural studies.